Metal chloride hydrates as Lewis acid catalysts in multicomponent synthesis of 2,4,5-triarylimidazoles or 2,4,5-triaryloxazoles

Abstract

Uma série de nove hidratos de cloretos metálicos (ZnCl, 2H,O, SnCl, 2H,O, CdCl, 2H,O, MnCl2, 4H2O, CoCl2 6H2O, SrCl2 6H2O, NiCl2 6H2O, CrCl3 6H2O e CeCl3 7H2O) foi investigada como catalisadores ácidos de Lewis brandos e baratos na síntese multicomponente de triarilimidazóis. O melhor catalisador para as reações com benzila foi o SnCl2.2H2O, enquanto que para as reações com benzoína, o CeCl37H2O foi mais eficiente. Todas as reações foram efetuadas em EtOH como solvente. Estes catalisadores também foram empregados igualmente com sucesso na síntese de triariloxazóis.

A series of nine metal chloride hydrates (ZnCl, 2H,O, SnCl, 2H,O, CdCl, 2H,O, MnCl2, 4H2O, CoCl2 6H2O, SrCl2 6H2O, NiCl2 6H2O, CrCl3 6H2O e CeCl3 7H2O) was investigated as mild and inexpensive Lewis acid catalysts to promote the multicomponent synthesis of triarylimidazoles. Reactions starting from benzil showed the best results when SnCl2.H2O was used, while for benzoin as the starting material, CeCl .7H O was more efficient. All reactions were performed in EtOH as solvent. These catalysts were also successfully employed in the synthesis of triaryloxazoles.